@for $item from 1 to 10 {
    li:nth(#{$item}) {
        position: absolute;
        left: $item * 10px;
        top: $item * 10px;
    }
}

@for $item from 1 through 10 {
    li:nth-child(#{$item}) {
        position: absolute;
        left: $item * 10px;
        top: $item * 10px;
    }
}

$colors: red, green, blue;
@for $i from 1 through length($colors) {
    .color-#{$i} {
        color: nth($colors, $i);
    }
}

@each $item in $colors {
    $index: index($colors, $item);
    li:nth-child(#{$index}) {
        color: $item;
    }
}